1. Field of the Invention
The invention relates to a hydrodynamic coupling device, in particular a torque converter or fluid clutch, comprising: a housing arrangement, a turbine wheel provided in the housing arrangement, a lockup clutch arrangement enabling the optional production of a torque transmission connection between the turbine wheel and the housing arrangement, the lockup clutch arrangement comprising: at least one essentially annular friction element which is connected to the turbine wheel for rotation together about an axis of rotation and has a friction surface region, and a contact element which is connected to the housing arrangement for rotation together about the axis of rotation and can be used to act upon the frictional surface region of the at least one friction element to produce the torque transmission connection between the turbine wheel and housing arrangement.
2. Description of the Related Art
In hydrodynamic coupling devices of this type, particularly in a state in which at least part of the torque to be transmitted via a drive train is passed from the housing arrangement to the turbine wheel via the lockup clutch arrangement, torsional vibrations occurring in the drive system can be intercepted by the fact that a certain slip is permitted in the lockup clutch arrangement, so that torque peaks can lead to a relative rotation between the housing arrangement and the turbine wheel. This results in a comparatively large load on the components or surface regions which act frictionally on one another in the region of the lockup clutch arrangement, since the power loss which occurs at least when the torque fluctuations are relatively large and is intercepted by slip is converted into heat. In order to be able to meet the requirement for ever greater possible power losses in the region of the lockup clutch arrangement, systems have been developed as described, for example, in WO 00/03158, which corresponds to U.S. Pat. No. 6,293,380. In the hydrodynamic torque converter known from this publication, the lockup clutch arrangement has two friction elements which are coupled to the turbine wheel for rotation together and between which an intermediate friction element, which is coupled to the housing arrangement for rotation together, is positioned. The clutch piston which is joined to the housing arrangement radially within the friction surface region and acts as a contact element is used to bring the individual friction surface regions of the friction elements, of the intermediate friction element, of the clutch piston and of the housing arrangement into mutual interaction. The provision of a plurality of staggered friction surface pairings which can be brought into interaction with one another enables the friction surface made available as a whole to be significantly increased without taking up a substantial amount of structural space. This has the effect that even the power loss occurring in the slip mode can be distributed over a relatively large surface area and can therefore be better and more rapidly dissipated.
A disadvantage of the known coupling devices of the above-described type is that a connecting arrangement which “goes around” the outer circumference of the contact element is provided for connecting the friction element or friction elements to the turbine wheel. This connection takes up structural space and increases the weight of the coupling device. In addition, the arrangement of the additional mass in the radially outer region results in a particularly marked increase in the mass moment of inertia of the turbine wheel.
A further disadvantage of the known coupling device in view of the overall weight is the mounting of the radially inner region of the contact element on a section protruding for this purpose axially from the housing arrangement into its interior space.